PURPOSE OF THE STUDY.
The goal of this study was to investigate whether immunoglobulin (Ig)E levels to native and denatured hen’s egg proteins could be useful in differentiating those sensitized but clinically tolerant to egg, those allergic to raw but not cooked egg, and those allergic to both raw and cooked egg.
The study included 44 patients with a median age of 2.1 years who were divided into 3 groups on the basis of open food challenge results: egg tolerant, allergic to raw egg but tolerant to cooked egg (hardboiled or cooked at 180°C for 30 minutes), and allergic to both raw and cooked egg. Positive challenge was defined as having an immediate type reaction; patients with delayed or equivocal reaction were not included.
IgE levels to both native and denatured egg white, ovalbumin, and ovomucoid were measured. Serum samples were collected within 6 months of the food challenge that determined the patient’s tolerance/allergy.
Overall, higher titers of egg white–specific IgE correlated with an increased degree of allergy. IgE titers were higher to native proteins than to denatured ones; however, denatured proteins were more helpful in identifying sensitized but tolerant patients. IgE to native egg white was useful in determining cutoff values for raw egg allergic versus egg tolerant patients (1.6 kU/L) and also for raw and cooked egg allergic versus egg tolerant patients (4.1 kU/L) with sensitivity >80% and specificity 100%. Native ovalbumin was found to be best for distinguishing between raw/cooked egg allergy and tolerance to both. Native ovomucoid was best for distinguishing between raw egg allergy and tolerance to cook egg.
Using a panel of IgE tests to specific native and denatured proteins including egg white, ovomucoid, and ovalbumin can help improve diagnostic accuracy in patients with hen’s egg allergy.
Egg allergy is among the most frequently diagnosed food allergies in children. Complete elimination of egg can be difficult for patients and families due to widespread use in a Western diet. Many egg-allergic patients can tolerate cooked forms of egg, although egg white–specific IgE alone is often not helpful in predicting who will be tolerant. Using a combination of egg white IgE with testing to ovomucoid and ovalbumin may help in identification of cooked egg tolerant patients. It is still important to interpret the laboratory data in light of the clinical history and to consider oral food challenges before reintroduction of either cooked or uncooked egg products in a previously allergic patient.
- Copyright © 2015 by the American Academy of Pediatrics